The invention pertains to a maskless lithography system for transferring a pattern onto the surface of a target, and to a method for transferring a pattern onto a surface of a target using a maskless lithography system.
Ups to now, most commercially available lithography systems use a mask or reticle to transfer a pattern onto a surface of a target. For each new design, however, such a reticle has to be produced. Especially with ever increasing resolution requirements, now in the order of 100 nm, this has become more and more challenging. Furthermore, it reduces flexibility in chip production processes. Therefore, maskless lithography systems are being developed.
A certain class of these lithography systems is multi-beamlet systems. In such maskless lithography systems using a plurality of beamlets for transferring a pattern onto a surface of a target, a beamlets generator generates a plurality of beamlets, such as electron beamlets, ion beamlets, x-ray beamlets, or the like. These beamlets are usually focused onto the surface or a target and together or individually scanned over its surface. In these systems, the designed spot size of each beamlet usually is smaller than 50 nm, and in the order of 10,000 beamlets is to be used.
In case one or more beamlets should fail, however, as statistically becomes likely with such a large number of beamlets, entire wafers are rendered unusable at once, which has a large effect on costs and manufacturing time of wafers. This can in fact undo a considerable part of the advantage of a so-called massive multi-beamlet lithography system as regards throughput.